The present invention relates to mixed crystals comprising a) leavening agent and b) 0.1 to 5000 ppm by weight of crystallization aid, based on the total amount of the leavening agent, in the form of at least polymer, wherein when hydrophilic cellulose derivatives are used as crystallization aid, the amount thereof is reduced to less than 100 ppm by weight, based on the total amount of the leavening agents. The present invention further relates to the production of the mixed crystals and to the use thereof in the production of bakery products, as acid regulator in foods, in the production of cosmetics products, in the synthesis and formulation of pharmaceutical products, and also as blowing agent in industrial processes such as, for example, the production of foam rubber, or for fire-extinguishing formulations. The present invention relates, furthermore, to the production of bakery products.
For the production of porous bakery products, a gas is generated in the dough before and/or during the baking process, or the dough is admixed with gas in order to generate porosity in the baked product by virtue of the gas bubbles. In the simplest scenario, the dough is admixed, prior to baking, with a gas, usually air, for instance by intense beating of the dough or of one of its ingredients prior to mixing. The most well-known embodiment is the addition of beaten egg white to the dough. It is equally possible to incorporate a gas such as air into the dough through nozzles. Also known are methods in which steam loosens the dough, as in the production of flaky pastry. The gas usually used, however, is carbon dioxide, or carbon dioxide in a mixture with ammonia and steam. Carbon dioxide is generated, for example, biologically in the course of the fermentation of dough ingredients by yeasts (yeast dough) and/or by lactic acid bacteria (sour dough). Alternatively or additionally to the use of yeast or sour dough, carbon dioxide, or the carbon dioxide, ammonia and steam mixture, is also generated chemically by means of baking additives, known as leavening agents or, in common parlance, as “baking powders” which are added to the dough.
Leavening agents generally comprise at least one carbonate and, if it does not decompose solely due to temperature increase, an acidic or acid-forming substance. Optionally, in addition to carbonate, they also comprise carbamate. The carbonate and/or carbamate is selected in line with the baked article to be produced; for spiced cake or honey cake, for example, potassium carbonate is frequently used, while for flat bakery products it is common to use sodium hydrogencarbonate (former name: “sodium bicarbonate”), ammonium hydrogencarbonate (“ammonium bicarbonate” “ABC” for short), as sole carbonate or in a mixture with ammonium carbamate (“ammonium carbonate”). The acid or the acid-former must not adversely affect the taste, either itself or together with the nonvolatilizing residues of the carbonate or carbamate. Typically, compounds are used such as tartaric acid or its salts, such as potassium, sodium, potassium hydrogen and/or calcium tartrate, citric acid, calcium hydrogenphosphate, sodium hydrogen pyrophosphate or sodium aluminum phosphate. If the leavening agent comprises an acid or an acid-former, it is usually admixed with a release agent which prevents the premature formation of carbon dioxide by reaction of the carbonate with the acid or acid-former, the addition of flour or starch being customary for this purpose. The aforementioned ammonium compounds ABC and ammonium carbamate decompose solely due to temperature increase at not less than 60° C., without residue, to form carbon dioxide, ammonia, and water. At typical baking temperatures, all three components are obtained in gaseous form, and therefore all result in an increase in the porosity of the baked product. These compounds are typically used, consequently, without an added acid or acid-former, and so there is no need to add the release agent.
Ullmanns Encyklopädie der technischen Chemie, 3rd edition, Urban & Schwarzenhäuser, Munich—Berlin 1953, head words “Backpulver” [baking powder], or Ullmann's Encyclopedia of Industrial Chemistry, Sixth ed., 1999 Electronic Release, Wiley-VCH, Weinheim 1999, head word “Bread and other baked Products”, section 2.6 therein: “Leavening Agents”, provide a comprehensive overview of the known methods of producing porous bakery products using leavening agents. The preparation of ammonium compounds such as ammonium carbonate, bicarbonate, and carbamate by reaction of quantities of ammonia and carbon dioxide corresponding to the desired product, in aqueous mother liquor, at pressures and temperatures selected in line with the product, followed by removal and drying of the precipitate, has also been known for a long time and is described in, for example, Ullmann's Encyclopedia of Industrial Chemistry, sixth edition, 1999, Electronic Release, Wiley-VCH, Weinheim 1999, head word “Ammonium Compounds”, especially section 4: “Ammonium Carbonates”. The preparation of alkali metal carbonates and hydrogen carbonates is known as well.
Although these ammonium compounds are obtained in gaseous form at typical baking temperatures, it is common to add an anticaking agent to the leavening agent, in order to prevent the formation, referred to as “caking”, of lumps or sizable agglomerates in the powdery leavening agent. Anticaking agents used for this purpose are typically cornflour, magnesium oxide or magnesium carbonate in an amount of 2000 to 10 000 ppm by weight, based on the leavening agent. Optionally, in addition, inorganic salts are mixed with the anticaking agents.
The purpose of the anticaking agent, consequently, is to prevent the caking of the leavening agent that typically occurs under storage conditions. Instances of caking represent a major problem, particularly in the case of storage under pressure. These caked lumps are often difficult to loosen, and lumps remain in spite of loosening. The consequences of the caked-together lumps of leavening agent that remain are, primarily, unwanted, large gas bubbles during the baking process, and therefore large cavities in the baked article. These large cavities frequently go well beyond the desired pore diameter of 0.1 to about 5 mm for the pores in the baked article. This results in an undesirably high reject rate, since such baked articles, although containing individual cavities that are very large, otherwise consist predominantly of regions with an undesirably low porosity, and this makes the baked article hard and often visually unattractive as well. If the large cavities occur on the surface of the baked article, the layer of dough at the top, which is then thin, will bake substantially more quickly during the baking process, and will then have an unattractive dark brown or black discoloration. These bakery products are then unsaleable and increase the reject rate in production.
EP-A 1 161 872 discloses the use of anticaking agents based on hydrophilic cellulose derivatives. Sodium carboxymethylcelluloses are cited as preferred hydrophilic polymeric cellulose derivatives. There is disclosure to the effect that the cellulose derivative is used in an amount of at least 100 ppm by weight, based on the total amount of the leavening agent, more preferably at least 500 ppm by weight, with 1000 ppm by weight for example. EP-A 1 161 872 describes how the anticaking agent is added during or after the crystallization of the leavening agent, to the mother liquor. If the anticaking agent is added after the crystallization of the leavening agent, then leavening agent crystals form that are enveloped with anticaking agent—in other words, the crystals of leavening agent have an outer coat of anticaking agent. These coated leavening agents have a significantly reduced caking tendency as compared with uncoated leavening agents. In the case of storage under pressure, however, the anticaking agent coat is unable sufficiently to prevent caking (see example 5). If the anticaking agent is added during the crystallization of the leavening agent, then rod-shaped mixed crystals of leavening agent and anticaking agent are formed (see FIG. 4C). On account of the rod-shaped crystal morphology and hence a large contact area between the individual mixed crystals, however, the caking propensity of these mixed crystals is high (see example 4).
The use of cellulose derivatives and pectin within the food industry is multifaceted:
Hydrophilic cellulose derivatives are used in bakery products not only as anticaking agents but also, furthermore, as bulk-forming materials in an amount of, typically, 5% to 20% by weight, based on the bakery product (U.S. Pat. No. 4,678,672 and GB 745,926). Also known is the use of carboxymethylcellulose as a thickener in a typical amount of 0.5% to 1% by weight, based on the bakery product (EP-A 399 995).
US 2005/233046 describes stabilizers composed of microcellulose and hydrocolloid, e.g., pectin, in a weight ratio of 30/70 to 90/10. Optionally a salt is added, calcium chloride or potassium carbonate, for example, in an amount of 0.5% to 5% by weight. The use of these stabilizers in the production of foods is disclosed.
WO 01/5246 describes a method of producing compositions comprising at least one emulsifier and at least one bulk-forming substance. It is preferred to use compositions which additionally influence emulsifier, comprising, for example, a mixture of pectin and carrageenan in a weight ratio of 20:80 to 40:60, and a mixture of pectin and guar gum in a weight ratio of 30:70 to 70:30, and a leavening agent as well.
The prior art contains numerous disclosures of leavening agents covered with a protective film (a coat) of any of a very wide variety of anticaking agents. Described as a protective film, for example, are polysaccharides and derivatives thereof, more particularly starch, cellulose, manna, sodium alginate, methylcellulose, carboxymethylstarch, and carboxymethylcellulose (DE-A 28 21 703, WO 98/56595). Also used for coating particles are water-soluble cellulose esters (EP-A 461 886) or film-forming polymers such as methylcellulose, hydroxybutylmethylcellulose, sodium carboxymethylcellulose, hydroxyethylmethylcellulose or hydroxypropylmethylcellulose (DE-A 24 35 008). Optionally it is possible to use further anticaking agents such as magnesium silicate (WO 94/24860, U.S. Pat. No. 5,482,702) or phosphorous compounds (U.S. Pat. No. 5,468,716).
Part of the reason for the caking of the common leavening agents is the crystal morphology of the products. As a result of accretions and other crystal defects, the salts that are readily available industrially have a very rough structure. On account of the rough structure, these crystal forms may very easily become intermeshed, and mechanically stable bridges are formed between the individual crystals. These stable bridges produce the known high caking propensity in the products. FIG. 1 depicts an ammonium bicarbonate agglomerate, used typically as a leavening agent in the prior art.
The protective coat described (outer coat/shell) causes rounding of the otherwise rough crystal shape (see FIG. 1), by covering the crystal peaks and crystal accretions, and filling out the interstices, in order to reduce the intermeshing and hence agglomeration of the leavening agent crystals. The anticaking agent is used, consequently, as a spacer or for coating the rough crystal structure in order to round it off.
In all of the following specifications, fully crystallized, usually commercially available leavening agents are used, which, following crystallization of the leavening agent, are covered with an anticaking agent.
In summary, in the prior art set out below, the system which is present does not comprise mixed crystals of two or more substances, but instead comprises a pure crystal which has been coated/enveloped. As already described in the case of EP-A 1 161 872, coated leavening agents do have a significantly reduced caking tendency as compared with uncoated leavening agents. In the case of storage under pressure, however, the anticaking agent coat is unable sufficiently to prevent caking (see examples 2 and 3).
U.S. Pat. No. 3,930,032 discloses the coating of leavening agents with cellulose ethers for increasing the stability of the leavening agent. The leavening agent coated with cellulose ethers contains 3% of cellulose derivative.
EP-A-1 260 147 discloses a matrix of active components, examples being alkali metal or alkaline earth metal carbonates, and a polymeric material such as, for example, polysaccharides or cellulose. The weight ratio in the matrix of active component to polymer is 1:99 to 99:1, more particularly 40:60 to 60:40. Accordingly, the minimum level of the use of the polymer lies at 1% by weight of polymer, based on the alkali metal or alkaline earth metal carbonate.
WO 2004/48418 describes the preparation of carboxymethylcellulose (CMC) and the use of CMC in the production of bakery products. Example 16 describes a dough comprising, among other ingredients, sodium carbonate and CMC prepared in accordance with example 9. In relation to the dry dough, 0.9% by weight of sodium carbonate and 0.3% by weight of CMC are used, in other words 33% by weight of CMC in relation to the leavening agent.
U.S. Pat. No. 1,643,951 describes bakery products, more particularly meringues, comprising water-soluble pectin jelly. Bakery product dough compositions are described which include 5% by weight of pectin and 2% by weight of sodium carbonate, i.e., 250% by weight of pectin in relation to the leavening agent.
U.S. Pat. No. 2,791,508 describes the production of chips using algin or pectin. The examples in D5 disclose chip dough compositions comprising algin or pectin and calcium carbonate in a weight ratio as follows: (a) 1:0.12; (b) 1.75:0.12; and (c) 1:0.04, i.e., 800% to 2500% by weight of pectin or algin in relation to the leavening agent.
US 2005/118326 describes highly digestible foods. Example 6 describes a dough for tortillas, containing 0.28% of leavening agent, 1% of xanthan, and 0.3% of pectin, i.e., 464% by weight of polymer (xanthan and pectin) in relation to the leavening agent.
WO 97/12607 describes the encapsulation of alkali metal carbonates with an organic hydrophilic shell of, for example, xanthan or pectin. The organic shell makes up 5% to 60% by weight of the encapsulated alkali metal carbonates, i.e., about 5% to 150% by weight of polymer (e.g., xanthan or pectin) in relation to the leavening agent.
WO 94/24994 describes particles comprising a core of alkali metal carbonates or ammonium carbonates and a shell of hydrophilic polymers. Pectin or xanthan is described for example as polymer. The polymer coating accounts for 5% to 50% by weight of the dry coated particles, i.e., about 5% to 100% by weight of polymer (e.g., xanthan or pectin) in relation to the alkali metal carbonates/ammonium carbonates.
The use of anticaking agents is also widespread in fertilizers, since the fertilizers have to be comparatively stable in storage, as a result of their seasonal use.
Additionally used as anticaking agents, for example, are glues based on carboxymethylcellulose, mixed with fillers such as calcium carbonate or calcium oxide (DD-A 117 787); synthetic polymers such as, for example, carboxymethylcellulose or methylcellulose and a surface-active substance (U.S. Pat. No. 3,388,990/U.S. Pat. No. 5,472,476), hydroxypropylcellulose, sodium carboxymethylcellulose or hydroxypropylmethylcellulose (EP-A 246 719); or sodium carboxylmethylcellulose and a surface-active substance (SU-A 1570255).
To summarize, a disadvantage of the prior art is that, with the known measures for preventing the caking propensity, caking in storage under pressure cannot be adequately prevented. Consequently, these leavening agents have to be loosened in a separate step before use. Unfortunately, despite the loosening, caked lumps of the leavening agent remain, and lead to the formation of undesirably large gas bubbles and, consequently, of undesirably large cavities in the baked article.
Furthermore, mixtures of leavening agent and anticaking agent for use in continuous operation for the production of bakery products (automated baking lines) are disadvantageous. These mixtures are typically introduced in powder form via a metering means. In order to prevent caking of the mixture in the metering means, said means is continuously shaken. This shaking, however, causes separation of the leavening agent and the anticaking agent. The anticaking agent is therefore no longer present uniformly in the leavening agent, and there may be instances of caking of the leavening agent and hence of unwanted formation of ununiformly large cavities in the baked article. As a result, there is a risk of increased rejection.
A further disadvantage of the leavening agents from the prior art is their poor shelf life. Particularly in the context of the storage under pressure that is usual in this field of application, the prior art records instances of caking after just a few days, for both the coated leavening agents and for the pure powdery mixture of leavening agent and anticaking agent. Storage under pressure is usual, since lack of space dictates that the bags in question are stored on top of one another.
Accordingly, in spite of the use of anticaking agents and/or of a protective coating on the leavening agents, there are instances of caking, in other words of formation and lumps or sizable agglomerates, in the course of the storage and the use of leavening agents, and this continues to constitute an resolved problem. The caked lumps cause the formation of undesirably large cavities and hence an ununiform distribution of cavities.